Tension-regulator.



J. A. DAHLBERG. TENSION REGULATOR. APPLICATION FILED SEPT. 20. 1915.

Patented Feb. 13, 1917.

1 m mm ierrnrngornaen.

JOHN A. nantnnne, or rnooirtvn, nnw ronn.

TEJPII'SION- REGULATUE.

intense.

-Specification of Letters IPatent.

Patented net. an, acre.

Application filed September 20, 1915. Serial No. 51,.381.

To all whom it may concer Be it known that I, JOHN A. DAHLBERG, a citizen of the United States, residing at Brooklyn, New York, have invented certain new and useful Improvements in Tension- Regulators for Moving-Picture Machines, of which the following is a specification.

A principal object of the invention is to practically eliminate breakage of the film which is frequently caused by excessive or irregular tension upon the film between 'the lower magazine and the exposure mechanism. The tension on this part ot' the film is increased as the diameter of the film wound upon the spool in the lower magazine increases. At the same speed this causes a much stronger pull upon the film. To prevent breakage due to these causes T provide a spring-actuated friction clutch intermediate the spool shaft and its driver, a clutch operating device and a film engaged roller which engages the film in such manner as to cause a bend therein under constant pressure. Tension upon the film tends to till claimed hereafter.

cause the bend therein to straighten out and this tendency acts, through the roller and clutch actuating device upon-the clutch, to relieve the pressure of the spring and permit the clutch to slip more or less in accordance with the film tension.

T will now describe, in connection with the accompanying drawing, one' exemplitying embodiment of the invention, but it is to be undcrstgxnl that the invention is capable of embodiment I do not limit myself Figure l is aside elevation or sulticient parts of a moving picture machine to illustrate the application of the invention tluereto. Fig. 2 is an enlarged top plan of the parts included in the invention. l ig. 3 is aview from the left of Fig. 2, partly in section and partly in elevation.

- Fig. 4 1s a perspective detail of the film en gaged tension device.- I

. ltc'terence character- 1 designates the lower magazine containing film spool f2, driven by shat't 3. Fixed on this'shaftis a triction plate sh and connected to the shaft by a spline which permitsaxial movement 15a triction plate 5. Between these plates is mounted freely on the shaft a driver 6 which, in this'embodiment, is a sprocket to be driven by a chain, but might be a pulley for belt drive ore gear for gear drive. The

in other forms and to detailscxcept as is adaptable to Outwardly on shaft 3 is a collar 8, which may be adjustable iii desired. A clutch spring 9 is compressed between this collar and the movable friction plate. Normally,

therefore, the spring causes the be frictionally d and 5. 1

The exposure of film driving mechanism usually comprises a sprocket 10 located somewhat above the lower nianazine. The driving of the lower reel is to take up film after it leaves this lover sprocket or other final element or the exposure mechanism and the variations in tension which it is desired to compensate for occur between this sprocket, or similar part of the machine, and the lower reel. I therefore establish a bend in the film as at B, or other suitable point, between the point 10 and themed and this is accomplished by providing a roller 11',

Fig. i, slidably mounted in suitable frame 12 driver 6 to gripped between the plates conveniently placed upon the "top of the lower magazine. The roller is rotatably mounted in a yoke 13,avhich slides inguides 14. Pivotally. mounted on the frame 12 l5-is a bell crank 16, oi": which one has aniembcr 17 movably engaging the yoke 13.

The other arm 1 8 of the hell cranl: is con nected by a'suitable link 19 which may, as

shown, be a cord or wire, theiipper end of the clutch lever which will now-he described. The clutch lever 20 is usually adjustable to provide a variable-leverage and for this purpose it may be made in two parts 21 and 22, connected by suitable pin and slot connections 23,015 which at least one is provided with a bolt, 24-, so when the lever is adjustedsfor proper len. th the parts a may be securely tastened to ether. This composite lever is t'ulcrained at 25 upon an arm 26 secured to the magazine. The lower end of the lever is provided with a torlr E27, engaging groove 7' in movable clutch member 5, previously mentioned. The upper end of the lever is connected with'the link 19.

tlli

With the parts properly adjusted the con-.

stant pull on the film causes it to exert all times certain or constant pressure at the bend B upon roller 11 and this pres- ,sure'is transmitted through yoke. 1?, hell crank 16, link 19 and lever 20 to movable clutch member 5. This pressure opposes the pressure of spring 9. As the tension on the film increases, due to the increasing diameter of the mass of film uponthe reel or due to jerks in driving, the pressure of spring 9 will be opposed more strongly. In other words, the pressure of friction plates 4 and 5 upon the driver 6 Will be reduced more or less, depending upon the film tension and proper slipping will be permitted so that undue strains are'not transmitted to the film and breakage is substantially elimi nated. The arrangement is such that all play between the parts is taken up at all times by the continuous tension exerted by the bend in the film. The mechanism thus resists the pressure of spring 9 more or less at all times and automatically and immediately compensates for changes in the film tension. y

In actual use the mechanism has been found to be extremely sensitive and reliable in its action.

I claim:

1'. In automatic tension mechanism, the combination with a magazine, film spool and spool shaft, of a friction plate fixed on said shaft, another friction plate splined on the shaftfor end movement, a drive sprocket free on the shaft between said plates, a

under constant pressure, a movable mount ing for the roller, a bell crank actuated by the roller, a lever engaging the movable friction plate and a link connecting the lever I with said bell crank.

2. In an automatic tension mechanism, the combination with a magazine, spool shaft and a film winding spool rigidly mounted on the shaft, of a disk rigidly mounted on said shaft, another disk slidably mounted on the shaft, a continuously driven member loosely mounted on the shaft between said disks for driving the spool shaft, a bracket mounted on the side of said magazine, a lever pivotally connected intermediate its ends to said bracket and connected at its lower end to said sliding disk, a roller slid-ably mounted on said magazine for maintaining a bend under constant pressure in the film, a bell crank mounted on said magazine for forcing said roller toward the film, a link connecting the bellcrank to the upper end of the lever, and a coil spring mounted on said shaft for forcing the slidable 'disk toward, the continuously driven member,

JOHN A. DAHLBERG. 

